Low-dose clonidine and neostigmine prolong the duration of intrathecal bupivacaine-fentanyl for labor analgesia

Background: Intrathecal (IT) opioid and local anesthetic combinations are p opular for labor analgesia because of rapid, effective pain relief, but the duration of analgesia is limited. This study was undertaken to determine w hether the addition of clonidine and neostigmine to IT bupivacaine-fentanyl would increase the duration of analgesia without increasing side effects f or patients in labor. Methods: Forty-five healthy parturients in active labor were randomized to receive a 2-ml if dose of one of the following dextrose-containing solution s using the combined spinal-epidural technique: (1) bupivacaine 2.5 mg and fentanyl 25 mu g (BF); (2) BF plus clonidine 30 mu g (BFC); or (3) BFC plus neostigmine 10 mu g (BFCN). Pain, sensory levels, motor block, side effect s, maternal vital signs, and fetal heart rate were systematically assessed. Results: Patients administered BFCN had significantly longer analgesia (165 +/- 32 min) than those who received BF (90 +/- 21 min; P < 0.001) Of. BFC (123 +/- 21 min; P < 0,001), Pain scores, block characteristics, maternal v ital signs, Apgar scores, maternal satisfaction, and side effects were simi lar among groups except for nausea, which was significantly greater in the BFCN group (P < 0.05 as compared with BFC), Conclusions: The addition of clonidine and neostigmine significantly increa sed the duration of analgesia from IT bupivacaine-fentanyl during labor, bu t neostigmine caused more nausea. Although serious side effects were not ob served in this study, safety must be further addressed before the routine u se of multiple IT drugs is advocated.